Home » SQL & PL/SQL » SQL & PL/SQL » Select Statement (Oracle 10g )
Select Statement [message #409843] Wed, 24 June 2009 04:16 Go to next message
nijuchama
Messages: 2
Registered: June 2009
Location: Bangalore
Junior Member
Hi ,
I have a select statement which extracts 100 columns from a single table . All these columns are varchar columns . In this first 10 columns contains some data and remaining 90 columns contains null values.

I have another select statement on the same table with just 10 not null columns ( Above 10 columns).

Can any one tell me whether there will be any performance issue / any difference in memory usage between these two select statement.

Thanks
Niju Jose
Re: Select Statement [message #409852 is a reply to message #409843] Wed, 24 June 2009 04:30 Go to previous messageGo to next message
ThomasG
Messages: 3189
Registered: April 2005
Location: Heilbronn, Germany
Senior Member
Yes. How much ... depends.

If you want more detailed information on the difference, look at the explain plan of both queries, and trace both of them.
Re: Select Statement [message #409854 is a reply to message #409852] Wed, 24 June 2009 04:37 Go to previous messageGo to next message
nijuchama
Messages: 2
Registered: June 2009
Location: Bangalore
Junior Member
Hi ,
I just want to know is it a major impact or minor impact.

Thanks,
Niju Jose
Re: Select Statement [message #409856 is a reply to message #409854] Wed, 24 June 2009 04:40 Go to previous messageGo to next message
ThomasG
Messages: 3189
Registered: April 2005
Location: Heilbronn, Germany
Senior Member
The impact should be minor in most cases.
Re: Select Statement [message #409858 is a reply to message #409856] Wed, 24 June 2009 04:42 Go to previous messageGo to next message
pablolee
Messages: 2835
Registered: May 2007
Location: Scotland
Senior Member
Come on Thomas, you'll need to supply more than that. a 2000 word essay detailing the various possible circumstances and the effects based on them (with a summary page) would be good.
Cheers
Wink
Re: Select Statement [message #409863 is a reply to message #409858] Wed, 24 June 2009 04:51 Go to previous messageGo to next message
ThomasG
Messages: 3189
Registered: April 2005
Location: Heilbronn, Germany
Senior Member
Oh, I would PERHAPS do that for a general impact. Or a colonel impact. Or an adult impact.

But those major/minor things usually sort themselves out. Cool
Re: Select Statement [message #410144 is a reply to message #409843] Thu, 25 June 2009 08:06 Go to previous message
smartin
Messages: 1803
Registered: March 2005
Location: Jacksonville, Florida
Senior Member
Why would you select the 90 columns in the first place if you knew they would always be null?
Previous Topic: procedure error
Next Topic: sql statement executing for a very long > 1 hour
Goto Forum:
  


Current Time: Thu Dec 08 16:23:49 CST 2016

Total time taken to generate the page: 0.11785 seconds